The present technology relates to a photoelectric conversion device, a package structure therefor, and a method of manufacturing a photoelectric conversion device wherein a simple structure and an excellent light blocking-property are ensured and reductions in size (tallness, thickness) and cost can be realized.
Mobile apparatuses such as cell phones, PDAs (personal digital assistance), notebook type computers, etc. on which a small-sized camera module including an optical part such as a lens, etc. and a solid state imaging element is mounted have come to be used widely. With respect to the camera modules mounted on these mobile apparatuses, further reductions in size (tallness, thickness) and in cost are being demanded.
Normally, the camera module includes an image sensor chip formed with a solid state imaging element such as CCD (Charge Coupled Device), CMOS (Complementary Metal-Oxide Semiconductor), etc. and an imaging lens (optical lens) for forming a subject image on a light-receiving surface of the image sensor chip.
In order to reduce the size and weight of the image sensor package, there is used, for example, the wafer level chip size package (W-CSP) system in which the image sensor chip is packaged on a wafer level. A wafer formed with a multiplicity of image sensor chips is called, for example, a sensor wafer.
The imaging lens can be produced, for example, as a wafer scale lens including a single or plural substrates. The wafer scale lens has a single substrate (wafer) formed with a multiplicity of lenses (lens elements) or has a plurality of such substrates stacked on one another. The wafer scale lens is formed with a plurality of imaging lenses each having a single or plural lenses.
The sensor wafer formed with a multiplicity of image sensor chips and the wafer scale lens are bonded to each other, and the bonded body is then divided, to obtain modules (wafer scale camera modules) each including the image sensor chip and the imaging lens.
Heretofore, a large number of reports have been made on the structure and manufacturing method of camera modules (see, for example, nine patent documents and a non-patent document as follows:
Patent Documents
    1. Japanese Patent Laid-open No. 2002-290842 (paragraph 0011, FIGS. 1 to 3)    2. Japanese Patent Laid-open No. 2006-228837 (paragraph 0013, FIG. 1)    3. Japanese Patent Laid-open No. 2008-508545 (paragraphs 0021 to 0022, paragraphs 0031 to 0042, FIGS. 1 to 5)    4. Japanese Patent Laid-open No. 2008-512851 (claim 18, FIGS. 3 to 6)    5. JP-T-2009-512346 (paragraphs 0008 to 0010, FIG. 18)    6. Japanese Patent Laid-open No. 2010-2921 (paragraphs 0048 to 0060, FIG. 12)    7. Japanese Patent Laid-open No. 2010-45162 (claim 5, paragraphs 0048 to 0057, FIG. 4)    8. Japanese Patent Laid-open No. 2010-45650 (paragraphs 0009 to 0028, FIGS. 1 to 3)    9. Japanese Patent Laid-open No. 2010-11230 (paragraphs 0018 to 0021, paragraphs 0033 to 0039, FIGS. 1 and 3) herein after referred to as Patent Document 9Non-Patent Document    1. TESSERA, “Wafer-Level Optics,” [Searched Mar. 3, 2010], Internet<http://www.tessera.com/technologies/imagingandoptics/Pages).    Patent Document 9 titled “Camera Module” contains the following description.
FIG. 10 in the present disclosure, which is FIG. 3 in Patent Document 9, is a sectional view showing schematically the structure of a camera module according to related art. This camera module is composed mainly of a solid state imaging device 330 and a lens unit 320 including optical lenses. The solid state imaging device 330 is an image sensor of the wafer level chip size package structure, which is provided therein with penetrating electrodes 305 and solder balls 306, and in which a transparent plate-like member 304 is provided on a chip having an imaging area 308 formed at a surface of a semiconductor substrate 310. In addition, a multiplicity of microlenses (not shown) are formed in the imaging area 308, and each of the microlenses is formed with a light reception element. Lens elements 303 play the role of forming an image in the imaging area 308 of the solid state imaging device 330.
The solid state imaging device 310 and the lens unit 320 are respectively produced in separate steps, before being adhered to each other to complete the camera module. The transparent plate-like member 304 is bridgingly supported over the imaging area 308 by ribs 311 surrounding the imaging area 308, and a void is formed between the transparent plate-like member 304 and the imaging area 308. The void is filled up with air, to form a transparent layer 309. The ribs 311 are parts where scribe lines for dividing the adhered body into individual imaging element chips after formation of the imaging element chips are provided. The transparent plate-like member 304 includes a glass plate or the like, functions mainly to protect the imaging area 308 and to mount and fix thereon the lens unit 320 provided over the solid state imaging device 310, and has an infrared (IR) cut filter 307 formed with a laminate film on a surface thereof.
The lens unit 320 includes spacers 312 and wafer level lens substrate glasses 313 each provided with a lens element 303 in the center thereof. The wafer level lens substrate glasses 313 are transparent glass wafers having the same size as that of the semiconductor substrate in a wafer state before division into individual solid state imaging devices, and are stacked together through the spacer 312 surrounding the four sides of the imaging area 308. Specifically, the lens elements 303 are each supported by the spacer 312 and the other portion of the wafer level lens substrate glass 313 than the lens element portion; thus, the spacer 312 and the just-mentioned other portion are substantially realizing the function of a lens support.
The material of the spacers 312 is a resin or the like, which is not particularly limited; preferably, the spacers 312 as well as the ribs 11 are formed from a light-blocking material. A vapor-deposited metal film 301 shielding electromagnetic waves mainly is formed on the whole part of side surfaces on the four sides of the camera module, and the vapor-deposited metal film 301 is grounded through the solder balls 306 and the like. It is described that since the vapor-deposited metal film 301 functions also as a light-blocking film, covering the periphery of the lens support makes it possible to enhance the optical performance of the camera module as a whole. These are the contents of the description in Patent Document 9.
Incidentally, an example of the method of manufacturing a camera module by the wafer level chip size package (WLCSP) process in related art will be briefly described as follows.
FIGS. 11A to 11G illustrate methods of manufacturing a camera module and the configuration of the camera module according to the related art.
Examples of the method of manufacturing a camera module by the WLCSP process include a first method shown in FIGS. 11A to 11D and a second method shown in FIG. 11E to 11F. Incidentally, in the following description, it is assumed that a semiconductor wafer 170 having a plurality of image sensor regions 175 each formed with a multiplicity of imaging elements and a lens wafer formed with a plurality of lenses 151 have already been prepared.
The process of manufacturing a camera module by the first method will be outlined as follows. As shown in FIG. 11A, a transparent wafer 160 is bonded to a surface, on the side on which the image sensor regions 175 are formed, of the semiconductor wafer 170 for protecting the image sensor regions 175 of the semiconductor wafer 170 and for supporting the semiconductor wafer 170. The transparent wafer 160 is, for example, a glass substrate.
As shown in FIG. 11B and FIG. 11C, the bonded body, having the transparent wafer 160 and the semiconductor wafer 170, and the lens wafer 150 are respectively diced into individual pieces, whereby bonded-body chips having a structure in which the glass chip 132 and the semiconductor chip 142 are bonded to each other, and the lens chips 152, are produced. Then, as shown in FIG. 11D, the camera modules each having the bonded-body chip and the lens chip 152 bonded to each other are produced.
The process of manufacturing a camera module by the second method will be outlined as follows. As shown in FIG. 11E, the side, on which image sensor regions 175 are formed, of a semiconductor wafer 170 is bonded to a surface on one side of a transparent wafer 160. Further, a lens wafer 150 is bonded to a surface on the other side of the transparent wafer 160. Thus, the semiconductor wafer 170 is bonded to the one-side surface of the transparent wafer 160, and the lens wafer 150 is bonded to the other-side surface of the transparent wafer 160. As a result, a camera module in a wafer state (WLCM: wafer level camera module) is formed.
Next, as shown in FIG. 11F, the WLCM is diced into individual chips, to produce camera modules having a structure in which the lens chip 152, the glass chip 132 and the semiconductor chip 142 are stacked on and bonded to one another.
As shown in FIG. 11G, the camera module shown in FIG. 11D is subjected to a light-blocking treatment, whereby a layer (film) for blocking transmission of light is formed on the surfaces of the lens chip 152 exclusive of an effective lens surface and on the surfaces of the glass chip 132.